C-130 – INSTRUMENTATION (onboard behind sampling inlet)

LASER OPTICAL PARTICLE COUNTER [OPC]

• 256 size intervals @ nominal 0.1 < Dp < 7.0m m; 1-3min resolution
• Thermal analysis – sizes at approx. 30, 150, 300C(Refractory). Volatility at 150C suggests sulfuric acid or low temp volatile species present while residue at 300C suggest refractory components including soot.
• Calibration based upon ammonium sulfate non-absorbing aerosol needs correction for other refractive indices – including 300C sootlike residuals.
• Reduced counting efficiency in 0.1-0.2m range – needs correction
• C-130 Inlet losses expected for sizes increasing above about 3m m
• Operated "dry" – usually 20-40%RH by using 50/50 dilution flow
• Flow uncertainties estimated at +/- 10%

• 40 size intervals; nominal 0.006 < Dp < 0.25m m; 1-3 min. resolution
• Thermal analysis – sizes at approx. 30, 150, 300C.
• Calibration intrinsic but checked with latex spheres
• Some losses expected at smaller sizes below about 0.01m m
• Some count errors expected above about 0.2m m
• Operated "dry" usually at less than 20%RH using dried sheath air flow
• Flow uncertainties estimated at +/- 10%

CONDENSATION NUCLEUS COUNTER [CNambient, CNhot-300deg.C and UltrafineUCN]

• CN and CNhot are number concentrations for nominal Dp>13nm, 1Hz
• CNhot/CN ratio can be used as indicator of polluted vs. clean air
• Ultrafine UCN are number concentrations for nominal Dp>3nm
• Flow uncertainties nominally +/-5%
• Elevated counts can occur in cloudy regions due to droplet shatter on inlet